1. Field of the Invention
The invention relates to a tamper-proof container closure having a tamper-proof ring. When closed on the container, the tamper-proof ring engages the exterior surface of the wall of the container and is torn away from the rest of the closure the first time the closure is opened.
2. Description of the Prior Art
Various types of closures are known. One of the most frequently used types is the screw cap closure in which a tamper-resistant ring is retained by the lower edge of the threaded portion of the container upon opening.
Another type of closure is the closure plug which is used, for example, on tubes holding effervescent vitamin tablets. In this type of closure, the tamper-proof ring is retained by the lip or flange of the tube. The inside of the ring is provided with a head which, by means of different oblique surfaces, allows the plug with the ring to be fitted on the tube but the ring is retained on the tube upon opening. However, because of the elasticity of the plastic, such a closure cannot be made absolutely safe. It is possible, when opening the closure, to slip the ring over the edge of the tube without using any tool and without tearing the ring away from the plug.